On Tue, Oct 30, 2018 at 03:11:02PM -0700, Douglas Anderson wrote: > I started out this series trying to make sysrq work over the serial > console on qcom_geni_serial, then fell into a rat's nest. > > To solve the deadlock I faced when enabling sysrq I tried to borrow > code from '8250_port.c' which avoided grabbing the port lock in > console_write(). ...but since these days I try to run with lockdep on > all the time, I found it caused an annoying lockdep splat (which I > also reproduced on my rk3399 board). ...so I instead changed my > qcom_geni_serial solution to borrow code from 'msm_serial.c' > > I wasn't super happy with the solution in 'msm_serial.c' though. I > don't like releasing the spinlock there. Not only is it ugly but it > means we are unlocking / re-locking _all the time_ even though sysrq > characters are rare. ...so I came up with what I think is a better > solution and then implemented it for qcom_geni_serial. > > Since I had a good way to test 8250-based UARTs, I also fixed that > driver to use my new method. When doing so, I ran into a missing > include in serial_core.h. NOTE: I didn't have a way to test > msm_serial.c at all, so I didn't switch that (or all other serial > drivers for that matter) to the new method. > > NOTE: from a serial point of view v2 is the same as v1 but I've > removed the extra kgdb-related patches and made it obvious that this > is really for all sysrq, not just kgdb. I've also generally tried to > curate the CCs more properly. It seems your forgot console people to Cc. > > > Douglas Anderson (5): > serial: qcom_geni_serial: Finish supporting sysrq > serial: core: Allow processing sysrq at port unlock time > serial: qcom_geni_serial: Process sysrq at port unlock time > serial: core: Include console.h from serial_core.h > serial: 8250: Process sysrq at port unlock time > > drivers/tty/serial/8250/8250_aspeed_vuart.c | 6 +++- > drivers/tty/serial/8250/8250_fsl.c | 6 +++- > drivers/tty/serial/8250/8250_omap.c | 6 +++- > drivers/tty/serial/8250/8250_port.c | 8 ++--- > drivers/tty/serial/qcom_geni_serial.c | 10 ++++-- > include/linux/serial_core.h | 38 ++++++++++++++++++++- > 6 files changed, 63 insertions(+), 11 deletions(-) > > -- > 2.19.1.568.g152ad8e336-goog > -- With Best Regards, Andy Shevchenko
